Refining of petroleum oil



Patented Jan. 14, 1936 UNHTED STATES PATENT OFFICE REFINING OF PETROLEUMOIL No Drawing. Continuation of application No.

164,131, January 27, 19 tion December 9, 1925,

27. Division of applica- Serial No. 74,395. This application October 31,1929, Serial No. 403,911

2 Claims.

This application is a continuation of my copending application, SerialNo. 164,131, filed January 27, 1927, which in turn is a division of anapplication filed by me, Serial No. 74,395, filed on December 9, 1925and which has matured into Patent 1,839,114, Sept. 29, 1931.

This invention relates to improvements in the refining of petroleumoils, and refers more particularly to the subjection of the lightergravity liquid products produced in petroleum cracking to the action ofvarious refining agents for the purpose of removing or convertingobjectionable color-forming, odor-forming, sulphur and analogousobjectionable compounds.

The essence of the present invention resides in the utilization, as arefining agent, of substantially sulphur-free inorganic or organicacids, or a combination of organic and inorganic acids as the solerefining agent, or in combination with any other suitable refining agentor any combination of refining agents to accomplish the purpose aboveset forth.

I have discovered that when the lighter gravity liquid products producedin petroleum distillation and cracking are subjected to the action ofconcentrated sulphuric acid, for the purpose of refining and removingobjectionable compounds, the strength of the concentrated acid producesan objectionable reaction, namely, the oxidation of compounds present,particularly in cracked distillates, reacting in such manner as to leavein the refined oil substances which bring about an unstable condition inthe oil with respect to color and odor, where the oils are notredistilled.

To overcome this objection, various experiments were carried out, and Ihave discovered that it is possible to substitute for the concentratedsulphuric acid substantially sulphur-free inorganic'or organic acids,either alone or in combination. Further, it is possible to overcome theobjections pointed out by preceding the treatment with concentratedsulphuric acid with the step of subjecting the oil to the action of thesubstantially sulphur-free acids above set forth.

It may be pointed out that it is the essence of the present invention touse, essentially as a refining agent, the substantially sulphur-freeorganic or inorganic acids herein set out, in combination withconcentrated sulphuric acid, which, of course, includes the step ofsubjecting the oil first to the action of the substantially sulphurfreeacids before described and then to the sulphuric acid. treatment.

The invention contemplates the use of these refining agents, either ofthemselves or as separate steps, in a method of refining the oil, incombination with other treating agents including plumbite (lithargedissolved in an alkaline solution such as sodium hydroxide, potassiumhydroxide, and others), caustic soda, and other alkalies, earthyadsorbent agents, copper salts and the like.

By the term "substantially sulphur-free acids as used in thespecification and claims, I mean an acid which contains no sulphur inits molecular composition. This term does not refer to the presence ofsmall or accidental amounts of sulphur present in the materials fromwhich the acid was made or introduced during the course of commercialmanufacture, in other words, it does not refer to impurities whichcontain sulphur.

Among some of the inorganic acids contemplated for use in the presentinvention may be listed nitric acid, hydrochloric acid, orthophosphoricacid and metaphosphoric acid. These inorganic acids pointed out may beused alone or may be mixed with each other. For instance, one mixture ofinorganic acids which has been found suitable for the purpose comprisesa small proportion of nitric acid in one of the phosphoric acids.

Among the organic acids contemplated by the present invention may belisted the following: acetic (preferably glacial), chloracetic, and thelike. These organic acids may be used alone or in combination with eachother in suitable proportions, and the invention also contemplates thatthe organic acids may be mixed with the inorganic acids. As anillustrative example of the proportions in which these acids are mixed,phosphoric acid and acetic acid may be taken, as an example. Preferably,the acetic acid in the mixture is always less than 50% by volume of themixture, especially where the glacial acetic acid is used, for thereason that this acid is soluble in the oil and requires a largerproportion of phosphoric acid to reduce this solubility. This points outthat the properties of these acids must be considered in their use.Another suitable mixture is the introduction of a small percentage ofnitric acid, for example, 5 to 10%, with phosphoric acid or with aceticacid. The percentage of nitric acid, while not limited to the amountshown, must be kept as a smaller percentage relatively to the other acidin order to cut down its oxidizing properties, and thus obtain thebenefits of the mixed acids. On the other hand, the addition of nitricacid to acetic acid or phosphoric acid strengthens them by adding someoxidizing value to these relatively weak acids.

The present invention contemplates more particularly the refining ofwhat are known as cracked distillates, and more particularly thosecracked overhead products of end boiling point commercially satisfactoryto the trade which are produced directly from the cracking process.

The claims are as follows:

1. Steps in the process of refining a lighter gravity liquid productproduced from the cracking of petroleum oil, comprising subjecting theoil first to the action of a mixture of nitric and acetic acids, andthen to the action of concentrated sulphuric acid, to remove or convertobjectionable compounds present in said lighter gravity liquid product.

2. Steps in the process of refining a lighter gravity liquid productproduced from the cracking of petroleum oil, comprising subjecting theoil first to the action of acetic acid, and then to the action ofconcentrated sulphuric acid, to remove or convert objectionablecompounds present in said lighter gravity liquid product.

J ACQUE C. MORRELL.

